I am after some advice on what i should use for a sub floor for slate tiles.

I have just built a kitchen extension and the floor is now part existing floorbaord and 22mm ply in the extension. The floor looks pretty flat and I have purchased brazillian slates for the floor.

I was intending on fixing 4/6mm plywood over the existing floor prior to laying the slate but have been advised to use Wedi board as opposed to plywood. I am a bit tight for height as my tiles are 10mm and I don't want to be proud of the french door threshold

I have been looking into Wedi board and other alternatives and have been now advised that Ekoboard will be fit for purpose. This is much cheaper than Wedi board.

I am not an experienced tiler so want to make sure I get the sub floor as good as I can.

The kitchen area is around 32m2 and it will be a warm area due to heat from an Aga cooker and radiator.

So basically, ply vrs wedi vrs ekoboard? Would greatly appreciate some advice on what I should do with the sub floor.

Are you tiling before the kitchen goes in....by this i mean is it an empty room..?

If so i would lift the floorboards and noggin the joists every 300mm to strengthen the joist area then re-lay 22mm ply fixing this down every 300mm or so...

Then lay an un-coupling membrane and tile onto this...using suitable adhesive and grout from your preferred manufacturer.

dave, thanks for your reply, however, the size of my kitchen does not really lend itself to lifting all the board due to size of existing kitchen and stuff in there.

I am happy that the existing floor is solid enough and all the boards and well fixed, but as I said in original post, just wondered if wedi board/ekoboard would be worthwhile to lay on top of the existing/new floor to give that additional 'level' and also allow for some flex

Originally Posted by neilgall

dave, thanks for your reply, however, the size of my kitchen does not really lend itself to lifting all the board due to size of existing kitchen and stuff in there.

I am happy that the existing floor is solid enough and all the boards and well fixed, but as I said in original post, just wondered if wedi board/ekoboard would be worthwhile to lay on top of the existing/new floor to give that additional 'level' and also allow for some flex

If you are happy there is NO VERTICAL movement and the existing floor is well screwed at 300mm centres then all you need to do to be safe is to follow Dave's advice and fix a decoupling membrane such as Schluter Ditra or Dural and that will deal with any minor lateral movement you may have or get

Kev

Kev